A strong earthquake has struck far off the South Pacific island nation of Tonga, but there were no immediate reports of damage or injuries.

The US Geological Survey said the 7.6 magnitude quake struck about 541 miles south of Nuku'Alofa on Tonga. The quake struck at a depth of 24 miles.

The Pacific Tsunami Warning Centre did not issue a tsunami alert, but its report on the quake said sea level readings indicated that a tsunami was generated.

The quake hit 112 miles from New Zealand's remote, volcanic Kermadec Islands. The remote outpost is generally uninhabited aside from a weather station and a hostel for visiting New Zealand scientists and staff.

New Zealand Civil Defence officials issued but then quickly cancelled a tsunami warning.

Another 7.6 magnitude earthquake struck the region in July, but the eight New Zealand staffers at the Raoul Island outpost at the northern end of the Kermadecs were unharmed.

The region lies on the Ring of Fire - an arc of earthquake and volcanic zones that stretches around the Pacific Rim. About 90% of the world's quakes occur in the region.